Callbaq

NAME

Callbaq - A callback queue for workflow control.

Lightweight, Zero Dependency.

SYNOPSIS

var Callbaq = require('callbaq');
var workflow = new Callbaq();

// kickoff
workflow.start("new world!");

// add callback functions
workflow.add(function (cbq, input) {
        console.log("1: hello world : " + input);
        cbq.next("y0y0");
});
workflow.add(function (cbq, input) { console.log("2: here we go : " + input); });

// output:
// 1: hello world : new world!
// 2: here we go : y0y0

Or fire it later, also try using aliases methods

// add callback functions
workflow.add(function (cbq, input) {
        console.log("1: hello world : " + input);
        cbq.resolve("y0y0");
});
workflow.then(function (cbq, input) {
        console.log("2: here we go : " + input);
        return "knock knock";
});
// fire
var door = workflow.start("new world!");

// output:
// 1: hello world : new world!
// 2: here we go : y0y0
// content of door: "knock knock"

DESCRIPTION

callbaq is a lightweight callback queue for workflow and callback control with Zero Dependency.
Convert nested callback hell into serial procedural coding style, which is more readable, writable, and maintainable.

Work standalone, or with other modules.

INSTALLATION

npm i callbaq

METHODS

new

Get a new callback queue / flow.

var Callbaq = require('callbaq');
var callbaq = new Callbaq();

start

Start and walk through the workflow from step 0.

callbaq.start("new world!");

add / then

Add (append) a function for use as a callback, which will be executed at the next step.

The parameters for callback are:

1. callbaq instance of the current callback queue.
2. params from start() or the output of previous (step) callback function.

callbaq.add(function (cbq, input) {
        console.log("something cool : " + input);
        cbq.next("a secret");
});
callbaq.then(function (cbq, input) {
        console.log("finished with " + input);
});

next / resolve

Check out from the current step and pass result to next step / callback function when works are done.

callbaq.add(function (cbq, input) {
        cbq.resolve("A master piece");
});
callbaq.then(function (cbq, input) {
        cbq.next("A master piece");
})

EXPERIMENTAL use of Methods

The following methods are for EXPERIMENTAL usage and might change in the future.

Avoid using them if possible.

cbq

Similar to add(). Returns the queue array.
If called with a function object, the function object will be append into queue.

var old_queue = callbaq.cbq();
var new_queue = callbaq.cbq(function(cbq){ cbq.next("did something") });

current_step

Get or set current step number.
Workflow could be changed by calling this method with value.

var current_step_number = cbq.current_step();

// start over from the first step
var new_step_number = cbq.current_step(0);
cbq.next("some params");

step

Call specific step.

callbaq.step(3, "some params");

ATTRIBUTES

The following methods are for EXPERIMENTAL usage and for Expert Only, might change in the future.

Avoid accessing them directly if possible.

dataqueue

The queue of data awaiting for being input of callback functions, Array of any.

_cbq

The callback queue, Array of function.

_current_step

Current step, in number.

Create with custom initial values

var dataqueue = [1, 2];

// new with default values
var callbaq = new Callbaq({dataqueue: dataqueue});
callbaq.add(function (cbq, input) {
        console.log("something in data queue: ", input);
});
// will be executed immediately without needing callbaq.start()

EXAMPLES

You can have multiple callbaq instances working together or independently.

Just new some and enjoy them.

https://github.com/BlueT/callbaq/blob/master/example.js

Output:
	cb1, step 1: hello world :  [ 'new world!' ]
v->	cb1, step 2: here we go :  [ 'y0y0' ]
|	----------
|	cb2, step 1: Are you ok : bro
|	---> inner1: asking bro
|	---> inner2: he's fine
|	cb2, step 2: I am very ok : Let's rock N roll
|	----------
^->	cb1, step 3: here we go :  [ 'hEy Lo' ]
	----------
	something in data queue:  1
	and guess what!  [ 'lala' ]
	from dataqueue again!  2

AUTHOR

BlueT - Matthew Lien - 練喆明 [email protected]

CREDITS

Waiting for Your Name here.

BUGS

https://github.com/BlueT/callbaq/issues

CONTRIBUTE

You can do a Fork, fix bug or improve code, and send a PR.
Or you can file a issue for bugs or improvements.

If you find this module useful, please give me a Star, I'll be happy whole day.

Hope this module can save your time, a tree, and a kitten.

SEE ALSO

AnyEvent::CallbackStack - Perl version https://github.com/BlueT/AnyEvent-CallbackStack

License